Preoperative Social Connection and Postoperative Outcomes in Adults Undergoing Surgery: A Systematic Review and Meta-analysis

Importance: Social connection is routinely recorded in surgical cohorts but rarely analyzed as an exposure, leaving its prognostic value unsummarized. Objective: To determine whether weaker preoperative social connection is associated with adverse postoperative outcomes. Data Sources: PubMed/MEDLINE, Embase, Scopus, Web of Science, CINAHL, PsycInfo, CENTRAL; inception to July 17, 2026; 33,301 records, 20,399 after deduplication. Study Selection: Studies of adults undergoing surgery with preoperatively ascertained social connection analyzed against a protocol-listed outcome; of 1,550 reports assessed, 454 reports of 445 studies were included. Data Extraction and Synthesis: PRISMA and MOOSE reporting; PROSPERO CRD420261449181. Estimate selection followed a frozen, direction-blind hierarchy; k denotes analysis weight units. Random-effects models used restricted maximum likelihood (REML) with modified Hartung-Knapp intervals; risk of bias, result-level Quality in Prognosis Studies (QUIPS); certainty, prognostic Grading of Recommendations Assessment, Development and Evaluation (GRADE). Artificial intelligence agents screened and extracted; 2 reviewers unblinded to their output confirmed all 39 principal-analysis estimate records. Main Outcomes and Measures: Postoperative all-cause survival (primary); early postoperative mortality, non-home discharge, unplanned readmission, any or major complications (secondary). Results: Poolable estimates came from 72 of 445 studies, mostly of marital status. Each principal analysis included up to 63,779 to 298,340 patients or procedures (upper bounds; cohorts recur across outcomes, so no overall total). For the primary outcome, postoperative survival, the confidence interval (CI) included 1 (9 units; hazard ratio, 1.37; 95% CI, 0.99-1.89; certainty very low). Weaker connection was associated with early postoperative mortality (8 units; odds ratio, 1.50; 95% CI, 1.12-2.01; certainty low) and non-home discharge (9 units; OR, 1.95; 95% CI, 1.35-2.81; certainty low). CIs included 1 for unplanned readmission (9 units; OR, 1.14; 95% CI, 0.98-1.33; certainty low) and complications (4 units; OR, 1.10; 95% CI, 0.96-1.25; certainty very low). All estimable prediction intervals included the null. No eligible study estimated the association with failure to rescue. Conclusions and Relevance: Preoperative social connection is a potential prognostic signal with substantial uncertainty. The largest association concerned discharge destination, partly shaped by the exposure itself, supporting early identification of support needs, not candidacy restriction. Whether changing social connection alters outcomes was not directly evaluated.